The present invention relates generally to the field of image processing, and more particularly to separating the foreground and the background in medical images.
Effective separation of the foreground and the background in medical images enables the detection of specific features in such images. For example, skin boundaries may be detected in mammograms and bone boundaries may be detected in X-Rays. Oftentimes, the foreground and background of medical images are separated by selecting a binarization threshold that is determined from a one dimensional histogram of the gray level values in the image. For example, the well-known method of Otsu assumes that an image contains two classes of pixels (i.e., foreground pixels and background pixels) that conform to a bi-modal histogram. A threshold is selected that minimizes the variance within each class (the intra-class variance) and thereby maximizes the variance between the classes (the inter-class variance).